Railroad vehicles as part of a modern traffic infrastructure are track-bound traffic and transport means which move for example in rolling fashion on or beneath one or two guide rails (tracks), in levitating fashion above or below a magnetic field or in a manner suspended from steel cables. Of the track-bound traffic and transport means mentioned, the most widely used are rail vehicles which are based on a wheel-rail system, which either have their own propulsion drive (railcar) or are pulled or pushed by a locomotive and in which predominantly steel wheels are guided with a wheel flange on two steel rails or tracks.
Such rail vehicles in regional traffic or long-distance traffic, in contrast to driverless subways and railroads for linking airport terminals, rely on the fact that a tractive vehicle driver evaluates distant signals and main signals, such as e.g. line free signal or line occupied signal, and derives corresponding driving actions therefrom.
As a result, generally in the case of driver-operated railroad vehicles and in particular in the case of corresponding rail vehicles, the following scenarios can occur:
Scenario 1:
Tractive vehicle drivers, like all other human beings bearing responsibilities, are occasionally inattentive or make errors of perception and therefore possibly initiate highly dangerous driving actions (accelerating the vehicle) or fail to carry out driving actions (failing to carry out a braking operation in the vehicle).
Scenario 2:
Tractive vehicle drivers may not always be available (e.g. owing to illness, strike, unplanned increase in driving tasks, etc.), with the result that railroad journeys possibly have to be cancelled.
The occurrence of these scenarios outlined could be eliminated by automatic signal recognition, but the latter has failed hitherto on account of the following problems:    A. the state of signals has not been able to be recognized reliably, without producing a communication device between the section or signal box and the rail vehicle.    B. abnormal signals such as e.g. damaged signals or temporary signals for construction sites have not been able to be recognized.    C. relevant signals have not been able to be reliably differentiated from irrelevant signals (e.g. from a branch line or the opposite direction).
The cited problems in the implementation of automated signal recognition and corresponding driving influencing of the railroad vehicle or rail vehicle have hitherto been attempted to be tackled by expensive additional investment in the line infrastructure, such as induction loops, computers along the line and communication installations between train and line components. Corresponding solutions are therefore economic only on lines of manageable length, such as, for example, subways or railroads between airport terminals.